I. Field of the Invention
The present invention relates to a roller bearing having spacers, in place of a cage, interposed between rollers.
II. Description of the Related Art
Japanese Patent No. 3549530 discloses a roller bearing having spacers, in place of a cage, interposed between rollers. Such a roller bearing allows a larger number of rollers to be mounted therein, and can provide increased load capacity.
The behavior of the spacers during operation of the bearing can be stabilized in the following manner as shown in FIG. 4. Specifically, surfaces of each spacer 8 that face the rolling contact surfaces of adjacent rollers 6 are formed into a concave shape for receiving the rolling contact surface, and the spacers 8 are guided by a bearing ring (an outer ring 2 or an inner ring 4, the outer ring 2 in this case). However, due to the concave shape of the spacers 8, the spacer 8 may receive force from each of the adjacent rollers 6, as indicated by thick arrows in FIG. 4, so as to be pressed in the radial direction of the bearing toward the inner circumference surface of a flange of the outer ring, though this depends on the shape of the spacer (the relationship of the gap between the concave shape and the bearing ring). Therefore, the bearing may rotate, with the spacers pressed against the bearing ring. In particular, when the spacers are pressed against a non-rotating ring, a breaking force acts on the spacers, and therefore seizing may occur when the rotation speed is high.
Hence, Japanese Patent No. 3549530 discloses that the surfaces of the spacers that come into contact with the roller-contacting surfaces of the rollers are formed into a flat face orthogonal to the circumferential direction of the bearing so that no radial force from the rollers is exerted on the spacers. However, the attitudes of the spacers are not always constant, so that the orthogonality of the spacer with respect to the circumferential direction of the bearing can be lost. The attitude of the spacer is corrected by the adjacent rollers. However, under the operation conditions wherein the bearing is reversed in its direction of rotation and is rapidly accelerated and decelerated, the attitudes of the spacers can be greatly disturbed. In such a case, a radial force is exerted on the spacers, and this is likely to result in heat generation at the guiding surface and abnormal wear of the spacers.